Process of preparing novel piperazinylethyl carbamates

ABSTRACT

Piperazinyl ethyl carbamates are obtained in good yield by reacting an N,N-dihydrocarbylcarbamate with triethylenediamine at an elevated temperature. The piperazinyl derivatives so formed are useful in the preparation of acid-soluble and acid-dyeable polyurethanes and as catalysts in the manufacture of polyurethanes.

United States Patent [1 91 Abbate et al.

[ Dec. 17, 1974 PROCESS OF PREPARING NOVEL PIPERAZINYLETHYL CARBAMATES [75] inventors: Franklin W. Abbate, North Haven;

William J. Farrissey, Jr., Northford, bothvof Conn.

[73] Assignee: The Upjohn Company, Kalamazoo,

Mich.

[22]v Filed: Dec. 22, 1972 Y [2]] Appl. No.1 317,607

7 Related US. Application Data [62] Division of Ser. No. 15,878, March 2, 1970, Pat. No.

[52] US. Cl 260/268 R [51] Int. Cl C07d 51/70 [58] Field of Search 260/268 R, 268 T [56] References Cited UNITED STATES PATENTS 2,979,502 4/196l Gailliot 260/268 R 3,138,597 6/1964 Schut 260/268 PH 3,719,680 3/1973 Abbate et al. 260/268 R Primary Examiner-Donald G. Daus Attorney, Agent, or FirmSteward & Steward 5 7] ABSTRACT 2 Claims, N0 Drawings PROCESS OF PREPARING NOVEL PIPERAZINYLETHYL CARBAMATES CROSS REFERENCE TO RELATED APPLICATIONS This is a division of application Ser. No. 15,878, filed Mar. 2, 1970, now US. Pat. No. 3,72 l ,674, issued Mar. 20, 1973.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to novel piperazinyl ethyl carbamates and to a process for their preparation and is particularly concerned with the preparation of piperazinyl ethyl carbamates by the reaction of an N,N-dihydrocarbylcarbamate with triethylenediamine at an elevated temperature.

2. Description of the Prior Art The only work previously described in the art in which triethylenediamine has been employed as a reactant to give a piperazine derivative is that of Ross et al, JACS 85,3999 (1963) who reacted 2,4-dinitrochlorobenzene with triethylenediamine to form the compound:

N-Cl

SUMMARY OF THE INVENTION The present invention comprises novel compounds of the formula:

wherein R and R are independently selected from the group consisting of hydrocarbyl of one to 12 carbon atoms, R is selected from the group consisting of CH and straight chain lower alkyl, and to a process for preparing such novel compounds.

The novel piperazine derivatives of this invention can be utilized as catalysts in preparing valuable polyurethanes including acid-soluble and acid-dyeable products.

Throughout this specification the term hydrocarbyl of from one to 12 carbon atoms" means the monovalent radical resulting when one hydrogen atom is removed from the parent hydrocarbon having the requisite number of carbon atoms. Illustrative of such groups are (a) alkyl, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl; (b) alkenyl, such as vinyl, allyl, butenyl, pentenyl, hexenyl, octenyl, dodecenyl, etc.; (c) aralykl, such as benzyl, phenylethyl, phenylpropyl, phenylhexyl, naphthylmethyl, etc.; (d) aryl, such as phenyl, tolyl, xylyl, naphthyl, bis-phenylyl, etc.; (e) alkaryl, such as ethylphenyl,

isopropylphenyl, ethylxylyl, methylnaphthyl, etc.; (f)

cycloalkyl, such as cyclobutyl, cyclohexyl, cyclooctyl, cyclodecyl, etc.; and (g) cycloalkenyl such as cyclobutenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl, cyclododecenyl, etc.; and isomeric forms of members of the above groups. The phrase straight chain lower alkyl in this specification means alkyl of from two to eight inclusive carbon atoms, as exemplified by ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl.

A wide variety of catalysts are employed in the preparation of polyurethanes and especially in preparing polyurethane foamsby the reaction of polyisocyanates with polyols in the presence of a fluorocarbon foaming agent. One of the most important of these catalysts is triethylenediamine which is employed in substantial quantities in the urethane industry in foam preparation as well as in the manufacture of other urethane products. It has been found that the novel piperazinyl ethyl carbamates of this invention are valuable-urethane catalysts which may be employed as a substitute for a part or all of the triethylenediamine commonly utilized in a production of polyurethanes by interaction of diisocyanates and polyols or in the production of polyureas by interaction of diisocyanates and polyamines. Methods for producing such polyurethanes and polyureas in the form of film, fibers and foams utilizing the conventionally employed diisocyanates and polyols together with the novel catalysts of this invention will be readily apparent to those skilled in the art. Conventional procedures for the synthesis of such polyurethanes are described by Saunders et al., Polyurethanes, Chemistry and Technology, Part II, lnterscience Publishers, 1964, pp. 299-451.

Examples of art-recognized polyols which can be employed alone, or as mixtures, in preparing polyurethanes include the following:

1. aliphatic diols, such as ethylene glycol, l,2- propylene glycol, 1,4-butanediol, l,2-hexane, 1,5- pentanediol, 1,2-hexanediol, etc.;

2. aliphatic triols, such as trimethylolmethane, trimethylolethane, l ,2,3-hexanetriol, l l l trimethylolhexane, etc.;

3. aliphatic tetrols, such as erythritol, pentaearythritol, etc.;

4. aliphatic pentols, such as arabitol, xylitol, etc.;

5. aliphatic hexols, such as mannitol, sorbitol, dipentaerythritol, etc.;

6. aniline-alkylene oxide diol adducts; and adducts prepared by reacting any of the above-named com pounds (1) through (5) above with one or more molar proportions of ethylene oxide, propylene oxide, 1,2-butylene oxide, or mixtures thereof.

Any of the prior art polyisocyanates can be used as reactants in preparing polyurethane products when utilizing the novel products .of this invention as catalysts e.g., 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, dianisidine diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate, m-xylylene diisocyanate, 1,5-naphthalene diisocyanate, and other diand higher polyisocyanates such as those listed in the tables of Siefken, Ann. 562, l22-l35 (1949). Preferred polyisocyanates, however, are products obtained by phosgenation of mixtures of methylene-bridged polyphenyl polyamines obtained by the interaction of formaldehyde, hydrochloric acid, and primary aromatic amines, for example, aniline, ochloroaniline, o-toluidine, or mixtures thereof. Such polyisocyanates are known in the art, e.g., US Pat. Nos. 2,683,730; 2,950,263; and 3,012,008; Canadian Pat. No. 665,495; and German specification 1,13 1,877.

In preparing polyurethane products employing the novel piperazinyl ethyl carbamates of this invention as catalysts, or as a part of the catalyst mixture, by reacare the tris polypropylene glycol phosphates producedby interaction of phosphoric and propylene oxide as, for example, described in US. Pat. Nos. 2,372,244 and 3,094,549.

DETAILED DESCRIPTION OF THE INVENTION The novel piperazinyl ethyl carbamates (I) of this invention are obtained by reacting an N,N-dihydrocarbylcarbamate with triethylenediamine at an elevated temperature.

The N,N-dihydrocarbylcarbamates employed as starting materials in the process of this invention have the following formula:

wherein R, R and R are as previously defined.

In conducting the process of this invention, the N,N-dihydrocarbylcarbamate employed as a starting material is preferably reacted with triethylenediamine in the presence of an inert organic solvent. The inert organic solvent can be any organic solvent which is inert under the conditions of the reaction, i.e., does not enter into reaction with any of the reactants employed or in any way interfere with the progress of the reaction. Suitable inert organic solvents include benzene, toluene, xylene, naphthalene, decalin, chlorobenzene, o-dichlorobenzene, bromobenzene, etc.

Advantageously, the reaction of the N,N-dihydrocarbylcarbamate with the triethylenediamine is conducted at a temperature ranging from about 80 C. to about 250 C. and preferably at a temperature within the range of about 100 C. to about 175 C. Approximately stoichiometric quantities of the two reactants are generally employed although, if desired, an excess of the carbamate can be utilized. The progress of the conversion of the N,N-dihydrocarbylcarbamate to the desired piperazine derivative can be followed by any of the appropriate analytical techniques such as infrared spectrographic analysis, etc. The desired piperazinyl ethyl carbamate can be isolated from the reaction mixture by conventional procedures in organic chemical operations such as by extraction, distillation, precipitation as the hydrochloric acid salt, etc.

The N,N-dihydrocarbylcarbamates utilized as starting materials are for the most part known compounds which can be prepared by methods conventional in the art for the preparation of N-substituted carbamates. A particularly convenient method involves the reaction of the appropriate chloroformate and appropriate dihydrocarbylamine; see, for example, H. von Pechmann, Ber, 28, 855 (1895) for a description of the preparation of ethyl N-methylcarbamate from methylamine and ethyl chloroformate as representative of the conditions required in preparing this series of compounds. Another method for the preparation of N,N- disubstituted carbamates involves the reaction of the corresponding N,N-disubstituted carbamyl halide with the appropriate alcohol for example, using the procedure described by Gattennann, Annalen 244,30 1888) for the reaction of carbamyl chloride itself with alcohols.

N,N-disubstituted carbamates can also be obtained by the alkylation of olefins with urethane (ethyl carbamate) as described by Mueller and Merten, Ber, 98, 1097 (1965) and by condensation of aldehydes with alkyl carbamates as described, for instance, by Bischoff, Ber, 7, 628 (1874).

The following examples describe the manner and process of making and using the invention and set forth the best mode contemplated by the inventors of carrying out the invention but are not to be construed as limiting.

EXAMPLE I- METHYLPIPERAZINYLETHYL N-METHYL-N-PI-[ENYLCARBAMATE The total of 3.18 grams of methyl N-methyl-N- phenylcarbamate together with 2.15 grams of triethylenediamine was added to 25 ml. of chlorobenzene and the mixture was refluxed for 24 hours.

After the reaction mixture had been poured into a small quantity of water, it was diluted with ether and then extracted with water followed by extraction with three portions of 1 N hydrochloric acid and finally extracted with an aqueous saturated salt solution. The aqueous layer was washed with two portions of ether. The combined organic layers were washed with three portions of an aqueous saturated salt solution and finally dried over magnesium sulfate. This phase contained the unreacted starting material which can be recycled.

The aqueous layers were combined, made basic with concentrated sodium hydroxide and extracted in a continuous extractor for about 16 hours. From the extract, after it had been dried over magnesium sulfate and after removal of solvent by evaporation, there was obtained 2.21 g. (83 percent of the theoretical yield) of the compound:

(III; 0 AW N(III:1,

which was identified by infrared spectroscopic and nuclear magnetic resonance analyses.

EXAMPLE II To 25 ml. of chlorobenzene there was added with mixing 1.65 grams of methyl N-methyl-N- (III; 0

having a boiling point of l09l 10 C. at 0.1 mm. Hg, which was identified by infrared spectroscopic and nuclear magnetic resonance analyses. The infrared spectrum (carbon tetrachloride solution) exhibited a maximum at 5.82;.t-

EXAMPLE III Utilizing the procedure of Example I but replacing methyl N-methyl-N-phenylcarbamate with:

ethyl N-propyl-N-isohexylcarbamate,

butyl N-ethyl-N-xylylcarbamate,

heptyl N,N-diphenylcarbamate,

octyl Nmethyl-N-n-hexenylcarbamate,

methyl N-ethyl-N-isopropylphenylcarbamate,

hexyl N,N-dicyclobutylcarbamate, or

pentyl N-tolyl-N-cyclohexenylcarbamate, there are obtained in good yield:

ethylpiperazinylethyl N-propyl-N-isohexylcarbamate,

butylpiperazinylethyl N-ethyl-N-xylylcarbamate,

heptylpiperazinylethyl N,N-diphenylcarbamate,

octylpiperazinylethyl N-methyl-N-n-hexenylcarbamate,

methylpiperazinylethyl carbamate,

hexylpiperazinylethyl,

and

pentylpiperazinylethyl N-tolyl-N-cyclohexenylcarbamate,

respectively.

Highly useful polyurethane foams can be prepared in which the novel piperazinyl ethyl carbamates of this invention are employed as the catalysts. The preparation of a typical foam product is set forth in the following preparation:

Using a mechanical blender, 100 parts by weight of polyol of equivalent weight 133 which is a blend of (i) an adduct of propylene oxide and a methylene bridged polyphenyl polyamine mixture obtained by acid condensation of aniline and formaldehyde and (ii) a glycerol-propylene oxide adduct, 2.3 parts by weight of a water-soluble silicone-glycol copolymer cell control N-ethyl-N-isopropylphenyl- N,N-dicyclobutylcarbonate,

agent and foam stabilizer, and 3.0 parts by weight of methylpiperazinylethyl N-methyl-N-phenylcarbamate are mixed together after which 32 parts by weight of a blowing agent, which is stabilized trichlorofluoromethane, is added. To the resulting mixture is added as rapidly as possible, 112 parts by weight of polymethylene polyphenyl isocyanate of equivalent weight 113 (PAPl). The mixture thus-obtained is stirred with a high speed stirrer for approximately 30 seconds and then is poured into an open mold (7 inches X 7 inches X 12 inches). The resulting foam, which is allowed to rise freely, is cured at room temperature (about 20 to 25 C.) for 7 days and afterwards subjected to physical testing. A polyurethane foam suitable for a wide variety of commercial applications, such as in the preparation of packaging containers, structural panels, etc. is obtained.

What is claimed is:

1. A process for preparing a compound of the formula:

wherein R is selected from the group consisting of methyl, ethyl, n-propyl and n-butyl, R is phenyl and R is selected from the group consisting of methyl and ethyl; which comprises the step of reacting a carbamate of the formula:

0 Brandi-0% at reflux temperature 

1. A PROCESS FOR PREPARING A COMPOUND OF THE FORMULA:
 2. The process of claim 1 wherein the said carbamate is methyl N-methyl-N-phenylcarbamate and the said reaction is conducted in the presence of chlorobenzene at reflux temperature. 